17,356 research outputs found
Non-local properties of multi-particle density matrices
As far as entanglement is concerned, two density matrices of particles
are equivalent if they are on the same orbit of the group of local unitary
transformations, (where the Hilbert space of
particle has dimension ). We show that for greater than or equal
to two, the number of independent parameters needed to specify an -particle
density matrix up to equivalence is . For
spin- particles we also show how to characterise generic
orbits, both by giving an explicit parametrisation of the orbits and by finding
a finite set of polynomial invariants which separate the orbits.Comment: 13 pages RevTe
Modelling the permeability of polymers: a neural network approach
In this short communication, the prediction of the permeability of carbon dioxide through different polymers using a neural network is studied. A neural network is a numeric-mathematical construction that can model complex non-linear relationships. Here it is used to correlate the IR spectrum of a polymer to its permeability. The underlying assumption is that the chemical information hidden in the IR spectrum is sufficient for the prediction. The best neural network investigated so far does indeed show predictive capabilities
The entangling and disentangling power of unitary transformations are unequal
We consider two capacity quantities associated with bipartite unitary gates:
the entangling and the disentangling power. For two-qubit unitaries these two
capacities are always the same. Here we prove that these capacities are
different in general. We do so by constructing an explicit example of a
qubit-qutrit unitary whose entangling power is maximal (2 ebits), but whose
disentangling power is strictly less. A corollary is that there can be no
unique ordering for unitary gates in terms of their ability to perform
non-local tasks. Finally we show that in large dimensions, almost all bipartite
unitaries have entangling and disentangling capacities close to the maximal
possible (and thus in high dimensions the difference in these capacities is
small for almost all unitaries).Comment: 6 pages, 1 airfoi
Rotor systems research aircraft predesign study. Volume 4: Preliminary draft detail specification
The RSRA requirements are presented in a detail specification format. Coverage of the requirements includes the following headings: (1) aircraft characteristics, (2) general features of design and construction, (3) aerodynamics, (4) structural design criteria, (5) flight control system, (6) propulsion subsystem, and (7) secondary power and distribution subsystem
JIGSAW: Preference-directed, co-operative scheduling
Techniques that enable humans and machines to cooperate in the solution of complex scheduling problems have evolved out of work on the daily allocation and scheduling of Tactical Air Force resources. A generalized, formal model of these applied techniques is being developed. It is called JIGSAW by analogy with the multi-agent, constructive process used when solving jigsaw puzzles. JIGSAW begins from this analogy and extends it by propagating local preferences into global statistics that dynamically influence the value and variable ordering decisions. The statistical projections also apply to abstract resources and time periods--allowing more opportunities to find a successful variable ordering by reserving abstract resources and deferring the choice of a specific resource or time period
Fields of influence of technological change in EC intercountry input-output tables, 1970-80
The paper considers a (static) portfolio system that satisfies adding-up contraints and the gross substitution theorem. The paper shows the relationship of the two conditions to the weak dominant diagonal property of the matrix of interest rate elasticities. This enables to investigate the impact of simultaneous changes in interest rates on the asset demands.
Normal mere exposure effect with impaired recognition in Alzheimer’s disease.
We investigated the mere exposure effect and the explicit memory in Alzheimer’s disease (AD) patients and elderly control subjects, using unfamiliar faces. During the exposure phase, the subjects estimated the age of briefly flashed faces. The mere exposure effect was examined by presenting pairs of faces (old and new) and asking participants to select the face they liked. The participants were then presented with a forced-choice explicit recognition task. Controls subjects exhibited above-chance preference and recognition scores for old faces. The AD patients also showed the mere exposure effect but no explicit recognition. These results suggest that the processes involved in the mere exposure effect are preserved in AD patients despite their impaired explicit recognition. The results are discussed in terms of Seamon et al.’s proposal (1995) that processes involved in the mere exposure effect are equivalent to those subserving perceptual priming. These processes would depend on extrastriate areas which are relatively preserved in AD patients
Processing of signals from an ion-elective electrode array by a neural network
Neural network software is described for processing the signals of arrays of ion-selective electrodes. The performance of the software was tested in the simultaneous determination of calcium and copper(II) ions in binary mixtures of copper(II) nitrate and calcium chloride and the simultaneous determination of potassium, calcium, nitrate and chloride in mixtures of potassium and calcium chlorides and ammonium nitrate. The measurements for the Ca2+/Cu2+ determinations were done with a pH-glass electrode and calcium and copper ion-selective electrodes; results were accurate to ±8%. For the K+/Ca2+NO−3/Cl− determinations, the measurements were made with the relevant ion-selective electrodes and a glass electrode; the mean relative error was ±6%, and for the worst cases the error did not exceed 20%
Some procedures for computerized ability testing
For computerized test systems to be operational, the use of item response theory is a prerequisite. As opposed to classical test theory, in item response models the abilities of the examinees and the properties of the items are parameterized separately. Hence, when measuring the abilities of examinees, the model implicitly corrects for the item properties, and measurement on an item-independent scale is possible. In addition, item response theory offers the use of test and item information as local reliability indices defined on the ability scale. In this chapter, it is shown how the main features of item response theory have given rise to the development of promising procedures for computerized testing. Among the topics discussed are procedures for item bank calibration, automated test construction, adaptive test administration, generating norm distributions, and diagnosing test scores
Peri-abelian categories and the universal central extension condition
We study the relation between Bourn's notion of peri-abelian category and
conditions involving the coincidence of the Smith, Huq and Higgins commutators.
In particular we show that a semi-abelian category is peri-abelian if and only
if for each normal subobject , the Higgins commutator of with
itself coincides with the normalisation of the Smith commutator of the
denormalisation of with itself. We show that if a category is peri-abelian,
then the condition (UCE), which was introduced and studied by Casas and the
second author, holds for that category. In addition we show, using amongst
other things a result by Cigoli, that all categories of interest in the sense
of Orzech are peri-abelian and therefore satisfy the condition (UCE).Comment: 14 pages, final version accepted for publicatio
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